Personalization of an official document is generally realized by a laser, which marks personalized elements, such as a name, a social security number, a validity date, etc, on the document body. Because of the value and importance associated with these data carriers, they are often subject of unauthorized copying and forgeries. As a consequence, security is one of the highest challenges for official documents.
To prevent counterfeiting activities, an official document must have sufficient observable security features to allow quick visual verification. Security elements such as guilloches are generally used to provide effective protection. Guilloches are precise and intricate repetitive patterns printed with ink on the document body or on specific layers laminated over said body, which prevent forged copies. Micro texts printed with ink all over an area of the document body or overlays can also be used as security elements. Many other security elements exist, such as Moiré patterns or Rainbow printing which is color variation on printed lines.
Pattern ink is either a standard ink, or a special ink such as an optical variable ink (OVI) which is an ink whose color changes with the observation angle, an infrared ink or an ultraviolet ink.
The printing process is inkjet process printing, offset process printing, flexographic printing, silkscreen printing or rainbow printing.
However, security is never optimal because counterfeiters always find how to copy and imitate or duplicate the security elements. Improving security features is a constant need for rendering counterfeiting more and more difficult.